计算机专业英语教程第5版翻译 绝对准确

这些调制解调器通常用于PCs和因特网应用。

Portable devices may also use a conventional dial-up modem; if so, they need to be connected to standard telephone jacks to access the Internet.

Portable 便携的 jacks 插座

便携的设备也使用传统的拨号调制解调器，假如这样，他们为了访问因特网需要连接到标准的电话插座上。 Standard dial-up Internet service range from free to about $ 25 per month.

标准的拨号因特网服务从免费到大约每个月25的范围内。

ISDN 综合业务数字网

@ Another dial-up option is ISDN.

另外一个拨号选择是综合业务数字网。

ISDN(integrated services digital network) allows digital transmission of data over ordinary telephone lines. transmission 传输

综合业务数字网允许通过不同的电话线进行数据的数字传输。

It requires a special ISDN adapter or modem and can transfer data up to 128 Kpbs.

它需要一个特殊的ISDN适配器或者调制解调器，可以传输数据达到128Kbps。

2. Direct Connections 直接相连

@ Unlike dial-up connections that only connect to your ISP's computer when you need to access the Internet, direct connections keep you continually connected to the Internet.

不像拨号连接那样，当你需要访问因特网时，只能连接到ISP的计算机上，直连使得你可以持续连接到因特网。

With a direct (always-on) connection, your PC is typically issued a static (nonchanging) IP address to be used to transfer data back and forth via the Internet.

issued 发布

通过直连，你的PC典型的发布一个用于经由因特网来回交换数据的静态IP地址。

PCs connected to the network always have an Internet connection available-Internet access requires only opening a browser.

电脑连接到网络总是有一个因特网连接可能的网络访问只需要打开一个浏览器。

@ Types of direct Internet connections include connecting through a school or office LAN, as well as DSL, cable, satellite, and fixed wireless connections.

Cable 电缆 satellite 卫星

直接的因特网连接类型包括通过一个学校或者政府机关的局域网以及数字用户线，电缆，卫星和固定无线连接进行连接。

Though, in theory, broadband Internet access can be up to 100 times as fast as a dial-up connection, actual speeds at the present time are more like 25 to 50 times as fast.

Theory 理论 broadband Internet access 宽带上网

虽然,在理论上,宽带上网可以快速到拨号连接的100倍,实际现在的速度则更像是25到50倍。

Typical download speeds for DSL and cable are about 1.5 Mbps;

数字用户线和电缆的典型地下载速度大约是1.5Mbps。

satellite and fixed wireless usually download data between 500 Kbps to 1 Mbps.

卫星和固定无线通常下载数据在500Kbps到1Mbps之间。

Virtually all of these services use slower upload speeds.

几乎所有这些服务使用较慢的上传速度。

The most significant characteristics of each of these types of broadband Internet access are discussed next. 每一种这些宽带上网的类型的最重要的特点将在后面讨论。

School or Office LAN

@ Most school or office LANs that offer a direct connection to the Internet lease a high-speed dedicated line (such as an ISDN or T1 line) from the telephone company or an Internet provider.

lease 租约 dedicated 专用的

大多数学校或者政府机关的局域网，提供一个与因特网直接相连的从电话公司或者因特网提供者那里租约一条高速专用线。

The speed of this type of Internet access depends on the speed of the connection between the school or offices and their Internet provider, as well as the speed of the LAN itself.

这种类型的因特网接入速度依赖学校或者政府机关和它们的因特网提供者间的连接速度，同样也依赖于局域网本身的